[lua] Add Sprite{ fromFile="...", oneFrame=true } to load just one frame

src/app/script/app_object.cpp

@@ -68,7 +68,8 @@ int load_sprite_from_file(lua_State* L, const char* filename,
     Commands::instance()->byId(CommandId::OpenFile());
   Params params;
   params.set("filename", absFn.c_str());
-  if (param == LoadSpriteFromFileParam::OneFrameAsImage)
+  if (param == LoadSpriteFromFileParam::OneFrameAsSprite ||
+      param == LoadSpriteFromFileParam::OneFrameAsImage)
     params.set("oneframe", "true");
   ctx->executeCommand(openCommand, params);
 

src/app/script/engine.h

@@ -167,6 +167,7 @@ namespace app {
 
   // Used by App.open(), Sprite{ fromFile }, and Image{ fromFile }
   enum class LoadSpriteFromFileParam { FullAniAsSprite,
+                                       OneFrameAsSprite,
                                        OneFrameAsImage };
   int load_sprite_from_file(lua_State* L, const char* filename,
                             const LoadSpriteFromFileParam param);

src/app/script/sprite_class.cpp

@@ -78,9 +78,13 @@ int Sprite_new(lua_State* L)
           if (const char* fromFile = lua_tostring(L, -1)) {
             std::string fn = fromFile;
             lua_pop(L, 1);
+
+            bool oneFrame = (lua_is_key_true(L, -1, "oneFrame"));
+
             return load_sprite_from_file(
               L, fn.c_str(),
-              LoadSpriteFromFileParam::FullAniAsSprite);
+              (oneFrame ? LoadSpriteFromFileParam::OneFrameAsSprite:
+                          LoadSpriteFromFileParam::FullAniAsSprite));
           }
         }
         lua_pop(L, 1);